From a weighing scale to a pole: a comparison of two different dosage strategies in mass treatment of Schistosomiasis haematobium.

Nordin P, Poggensee G, Mtweve S, Krantz I - Glob Health Action (2014)

Bottom Line:
We compared doses given by weight to doses given by height using descriptive statistics and regression.Our study shows that children with the same weight could qualify for up to four different dose levels based on their height.The largest variation of doses based on the WHO dose-pole will be found in children below 20 kg of bodyweight.

Affiliation: The Skaraborg Institute for Research and Development, Skövde, Sweden; per.nordin@skaraborg-institute.se.

ABSTRACT

Background: Clinical schistosomiasis in endemic countries is treated with a single dose of praziquantel per 40 mg/kg body weight. Treating according to weight, in resource-poor settings when thousands of doses are to be administered in mass treatment campaigns, is considered problematic. A calibrated dose-pole based on height was developed and is now used in mass treatment campaigns for determining the doses for schoolchildren. The dose-pole will generate dose errors since every child population contains individuals that are either short or tall for weight. The aim of this study is to explore whether the WHO praziquantel pole is a satisfactory dose instrument for mass treatment of S. haematobium.

Methods: In 1996 and 2002, 1,694 children were surveyed in the Kilimanjaro Region, Tanzania. We compared doses given by weight to doses given by height using descriptive statistics and regression.

Conclusions and interpretation: The WHO dose-pole for praziquantel is based on height of the patient; however, children with the same height will differ in weight. Our study shows that children with the same weight could qualify for up to four different dose levels based on their height. The largest variation of doses based on the WHO dose-pole will be found in children below 20 kg of bodyweight. Using bodyweight and tablet halves as the smallest tablet division unit to determine the doses of praziquantel, one only has to identify every 6th kilogram of bodyweight; the doses will then vary a lot less than when using the WHO dose-pole.

Figure 0004: Frequency weighted scatter plot of the differences in doses on the y-axis against the mean values of doses on the x-axis when comparing doses given by the dose-pole and doses using the weight approach. Reference lines included for mean differences as well as the limits of agreement.

Mentions:
Figure 4 shows a Bland-Altman plot for comparison of measures applied using our data. Again, the data points are presented as circles, where the size of the circle represents the number of observations in each point. The mean difference is 0.14 [0.13; 0.16], showing that a systematic difference exists and that the use of the dose-pole would on the average mean a slightly but statistically significant higher dose than the ‘gold standard’.

Figure 0004: Frequency weighted scatter plot of the differences in doses on the y-axis against the mean values of doses on the x-axis when comparing doses given by the dose-pole and doses using the weight approach. Reference lines included for mean differences as well as the limits of agreement.

Mentions:
Figure 4 shows a Bland-Altman plot for comparison of measures applied using our data. Again, the data points are presented as circles, where the size of the circle represents the number of observations in each point. The mean difference is 0.14 [0.13; 0.16], showing that a systematic difference exists and that the use of the dose-pole would on the average mean a slightly but statistically significant higher dose than the ‘gold standard’.

Bottom Line:
We compared doses given by weight to doses given by height using descriptive statistics and regression.Our study shows that children with the same weight could qualify for up to four different dose levels based on their height.The largest variation of doses based on the WHO dose-pole will be found in children below 20 kg of bodyweight.

Affiliation:
The Skaraborg Institute for Research and Development, Skövde, Sweden; per.nordin@skaraborg-institute.se.

ABSTRACT

Background: Clinical schistosomiasis in endemic countries is treated with a single dose of praziquantel per 40 mg/kg body weight. Treating according to weight, in resource-poor settings when thousands of doses are to be administered in mass treatment campaigns, is considered problematic. A calibrated dose-pole based on height was developed and is now used in mass treatment campaigns for determining the doses for schoolchildren. The dose-pole will generate dose errors since every child population contains individuals that are either short or tall for weight. The aim of this study is to explore whether the WHO praziquantel pole is a satisfactory dose instrument for mass treatment of S. haematobium.

Methods: In 1996 and 2002, 1,694 children were surveyed in the Kilimanjaro Region, Tanzania. We compared doses given by weight to doses given by height using descriptive statistics and regression.

Conclusions and interpretation: The WHO dose-pole for praziquantel is based on height of the patient; however, children with the same height will differ in weight. Our study shows that children with the same weight could qualify for up to four different dose levels based on their height. The largest variation of doses based on the WHO dose-pole will be found in children below 20 kg of bodyweight. Using bodyweight and tablet halves as the smallest tablet division unit to determine the doses of praziquantel, one only has to identify every 6th kilogram of bodyweight; the doses will then vary a lot less than when using the WHO dose-pole.